Finding the Sum of an Infinite Geometric Series

Find the sum, if it exists, for the following:

1. ⓐ $10 + 9 + 8 + 7 + \ldots$
2. ⓑ $248.6 + 99.44 + 39.776 + \ldots$
3. ⓒ $\sum_{k = 1}^{\infty} 4 , 374 \cdot \left(– \frac{1}{3}\right)^{k – 1}$
4. ⓓ $\sum_{k = 1}^{\infty} \frac{1}{9} \cdot \left(\frac{4}{3}\right)^{k}$